[clang] [clang-tools-extra] [Clang] Add builtins that deduplicate and sort types (PR #106730)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

I have started picking this back up after a break, sorry for the delays. I will address the comments in the coming days and send an updated version. #139730 also didn't really pick up, so I'm going to abandon the simpler attempt and double down on this PR.

https://github.com/llvm/llvm-project/pull/106730